DESCRIPTION (Adapated from Applicant's Description): This proposal is submitted in response to RFA HD-99-003 "Basic Science Research on Female Pelvic Floor Disorders." Described in this application is a comprehensive multidisciplinary basic and clinical science research program focused specifically on the relationship of childbirth to pelvic floor injury. Three research components are presented to include (1) a prospective analysis of the relationship between precise obstetrical events and subsequent pelvic floor dysfunction in 11,000 primiparous women; (2) a randomized trial of the effects of coached maternal pushing during the second stage of labor on postpartum pelvic floor function; and (3) utilization of a novel animal model to study the effects of vaginal trauma during pregnancy on lower urinary tract smooth muscle contractility and contractile protein gene expression. Sample sizes for the aims described in this application are based upon ad hoc power analyses. This proposal also describes the qualifications and experience of basic and clinical investigators at the University of Texas Southwestern Medical Center and Parkland Hospital who are committed to the study of childbirth related pelvic floor injury. Included are individuals with expertise in maternal-fetal medicine, urogynecology, and smooth muscle physiology. Existing resources include operational laboratories to support the basic science research described, a well functioning computerized perinatal database to support analysis of precise obstetrical events related to pelvic floor injury and an established, well-functioning infrastructure capable of completing randomized clinical trials. Integral to this infrastructure is a well-functioning state-of-the-art urogynecologic clinical laboratory. The major focus of this application is on its theme of multidisciplinary basic and clinical research focused specifically on childbirth which is the singular most important, predisposing factor to pelvic floor injury.